Lithium-ion and related batteries are being used in automotive and related transportation applications as a way to supplement, in the case of hybrid electric vehicles (HEVs), or supplant, in the case of purely electric vehicles (EVs), conventional internal combustion engines (ICEs). The ability to passively store energy from stationary and portable sources, as well as from recaptured kinetic energy provided by the vehicle and its components, makes such batteries ideal to serve as part of a propulsion system for cars, trucks, buses, motorcycles and related vehicular platforms. In one form suitable for automotive applications, individual battery cells are combined into larger assemblies such that the current or voltage is increased to generate the desired power output. In the present context, larger module and pack assemblies are made up of one or more cells joined in series, parallel or both, and include additional structure to ensure proper installation into the vehicle. Although the term “battery pack” is used herein to discuss a substantially complete battery assembly for use in propulsive power applications, it will be understood by those skilled in the art that related terms—such as “battery unit” or the like—may also be used to describe such an assembly, and that either term may be used interchangeably without a loss in such understanding.
Heat exchange systems are incorporated in order to cool such battery packs. Conventionally, heat exchange has been accomplished by directing air flow through two separate ducts, an inlet duct and an outlet duct. The inlet duct and outlet duct connect to the battery housing through two separate openings, which then requires two separate openings in the vehicle in order for the ducts to pass through. Air flow is conducted to the battery pack through the inlet duct that connects to the battery housing through a first opening in the floor of the vehicle and the battery housing; exhaust air is then directed out of the housing through the outlet duct that connects to the battery housing through a second opening in the housing and floor of the vehicle. Commonly, air enters at the front of the battery pack and exits the back end of the battery pack, thus cooling the battery cells in series.
This conventional design presents various challenges to the manufacture of the vehicle. First, the inlet/outlet arrangement requires at least two openings in the battery housing and floor of the vehicle, which can lead to tolerance and alignment issues in battery mounting. Second, cooling multiple battery cells in series can lead to problems associated with air flow resistance and unfavorable drop in air flow pressure. Third, conventional heat exchange methods and systems require multiple ducts within the battery pack (i.e., intake, intermediate, and exhaust ducts). Further, more complex design (e.g., multiple openings in vehicle body, multiple internal ducts inside battery pack) increases manufacturing costs. Thus, a need exists for an improved heat exchange system that addresses these issues, in order increase efficiency and reduce manufacturing costs and challenges.